Variable pressure grab hand

ABSTRACT

A CAM OPERATED GRAB HAND FOR GRASPING AND HOLDING A WORK PIECE FOR REMOVAL OF THE WORK PIECE FROM A METAL WORKING MACHINE. ONE FINGER OF THE GRAB HAND IS MOUNTED ON AND MOVABLE WITH A CONTROL ARM AND THE OTHER FINGER IS PIVOTALLY SECURED TO THE FIRST FINGER FOR BEING PIVOTED INTO ENGAGEMENT THEREWITH BY A CAM SECURED TO THE CONTROL ARM. A SPRING BIASING MEANS MAY BE ADJUSTED TO VARY THE PRESSURE OF THE GRIP APPLIED TO THE WORK PIECE BY THE PIVOTAL ENGAGEMENT OF THE SECOND FINGER WITH THE FIRST.

March 2,1971 c. HALBERSTADT 3,567,270

VARIABLE PRESSURE GRAB HAND Filed Aug. 6, 1969 INVENTOR. CHARLES C. HALBERSTADT BY 4 k 7 ATTORNEY United States Patent Oiifice 3,567,270 VARIABLE PRESSURE GRAB HAND Charles C. Halberstadt, Merrillville, 1nd,, assiguor to The Budd Company, Philadelphia, Pa. Filed Aug. 6, 1969, Ser. No. 847,864 Int. Cl. B66c 1/00 US. Cl. 294-104 4 Claims ABSTRACT OF THE DISCLOSURE A cam operated grab hand for grasping and holding a Work piece for removal of the work piece from a metal working machine. One finger of the grab hand is mounted on and movable with a control arm and the other finger is pivotally secured to the first finger for being pivoted into engagement therewith by a cam secured to the control arm. A spring biasing means may be adjusted to vary the pressure of the grip applied to the work piece by the pivotal engagement of the second finger with the first.

BACKGROUND OF THE INVENTION of this invention is to provide a grab hand that may be adjusted to grip a work piece with a predetermined force.

SUMMARY OF THE INVENTION The apparatus of this invention is a grab hand that may be moved on a support arm into a working position from a stored or retracted position. An actuating arm moves the grab hand on the support arm to effectively open and close the gripping fingers by moving a cam follower on one of the fingers along a cam secured on the support arm. One of the fingers includes an adjustable spring biasing means to control the pressure exerted by the fingers on the work piece While in the working position. A resilient material such a rubber or polyurethane foam may 'be secured to the gripping surfaces of the fingers to prevent marring the work piece during the gripping and moving thereof.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of the grip hand of this invention in the open position, phantom lines are used to illustrate the grab hand in closed or working position holding a work piece.

FIG. 2 is a view, in the direction of the arrows substan tially along the line 2-2 of. FIG. 1 showing the finger having adjustment means thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, as seen in FIGS. 1 and 2, the preferred embodiment of this grab hand, indicated generally by the numeral 10, includes a support arm 12 which may be fixed or movable between a receiving and delivering position, as desired.

The grab hand 10 is slidably supported on the support arm 12 by one end 14 of the rigid finger 16. The other end 18 of the finger 16 is provided with a gripping block 20 for contacting the work piece 22. The other finger 24 is pivotally secured to the rigid finger 16 by pivot pin 26 3,567,276 Patented Mar. 2, 1971 for movement there about. The pivotal finger 24 has a cam follower 28 on the end adjacent the support arm 12 for contacting a cam 30 secured to the support arm 12. The other end 32 of pivot finger 24 is provided with a gripping block 34 for contacting the work piece 22. The cam 30 is secured to support arm 12 for movement therewith and for contacting cam follower 28 for pivoting finger 24 about pivot pin 26 thereby securing the work piece 22 between the gripping blocks 20, 34.

The end 32 of finger 24 is pivotally secured to the main portion of the finger 24 by pivot pin 36. The end 32 includes the gripipng block 34 secured to a hollow cylinder 38 and a yoke structure 40 with one end secured to the cylinder 38 and the pivot pin 36 journaled in the arms of the yoke for pivotallly supporting the end 32. Extending between the arms of the other end of the yoke 40 is a stop bar 42 for contacting the main portion of the finger 24 for limiting the clockwise rotation of the end 32 about pivot pin 36, as viewed in FIG. 1. The hollow cylinder 38 contains a spring biasing unit including an adjustment screw 44 threadably mounted in the cylinder and engaging a pusher 46 which supports one end of a spring 48 with the other end of the spring bearing against a spacer plug 50 which extends from the end of the cylinder 38 and bears against the adjacent end at the main portion of finger 24.

The gripping blocks 20, 34, may be provided with a resilient gripping pad '52, 54, respectively, of a yieldable material such as rubber or polyurethane foam to protect the surfaces of the work piece. The adjustment screw 44 may be used to increase or decrease the clamping pressure between the gripping blocks 20, 34- by compressing spring 48 to increase the pressure or expanding the spring to decrease the pressure.

The grab hand is operated by an actuating arm 56 connected to a power source (not shown). The actuating arm 56 is pivotally connected to the end 14 of finer 16 by a pivot pin 16 for providing the power to slide the grab hand on the support arm 12.

In operation of this grab hand, the support arm 12 positions the grab hand 10 adjacent the work piece 22, the actuating arm 56 then moves the grab hand along arm 12 toward the cam 30. As the cam follower 28 passes over the cam 30, the finger 24 is pivoted about pivot pin 26 bringing gripping block 34 into contact with the work piece 22, thus, moving the work piece 22 into contact with gripping block 20 and securing the work piece 22 between the blocks 20, 34, as shown in phantom lines of FIG. 1. It is to be noted that as the work piece 22 is secured between the blocks 20, 34, the end 14 has contacted the cam 30 secured on the end at arm 12 and also acting as a stop to limit movement of the grab hand in the direction of the work piece '22. The support arm 12 then moves the grab hand 10, work piece 22 and actuating arm 56 to a desired position and then the actuating arm 56 is moved away from the cam 30 and such movement moves the cam follower 28 back along cam 30 and pivoting the arm 24 for moving gripping block 34 from contact with the work piece 22, thus releasing the work piece 22.

This novel grab hand may be used to hold a work piece in a fixed position if the support arm remains fixed, or to move a work piece along a production line from a receiving to a delivering position if the support arm is moveable therebetween.

I claim:

1. A work piece handling apparatus for grasping and transporting a work piece including a grab hand, a support arm for supporting said grab hand having a receiving position and a delivery position, and being moveable therebetween, and a power source for actuating said grab hand and moving said support arm between said positions; said grab hand having a gripping position and a release position and being moveable therebetween on said support arm; a cam means for moving said grab hand between said gripping and receiving positions; said grab hand including a first rigid finger having one end slidably supported on said support arm, a gripping block on the other end for engaging a Work piece at said gripping position, and a pivotal connection intermediate said ends; a second finger pivotally connected to said first finger at said pivotal connection, said second finger having a rigid portion and a pivotal end portion, a pivot pin journaled on one end of said rigid portion for pivotally connecting said pivotal end portion to said rigid portion, said pivotal end portion having a gripping block on the end most remote from the joint connected to said pivot pin, spring means biasing said pivotal end portion about said pivot pin towards said first finger and stop means limiting pivotal movement of said pivotal end portion toward said first finger, said rigid portion being pivotally connected to said first finger intermediate the ends thereof at said pivotal connection for moving said second finger gripping block into engagement with a work piece at said gripping position, and resilient means cushioning the contact of said gripping blocks with the work piece.

2. The handling apparatus as claimed in claim 1 wherein said cam means includes a cam secured to said support arm and a cam follower on the end of said second finger rigid portion opposite said pivot pin for cooperating with said cam for moving said second finger about said pivotal 4 connection whereby the work piece is secured between said gripping blocks in said gripping position and moved to the release position when said cam follower is not contacting said cam.

3. The handling apparatus as claimed in claim 1 wherein said spring biasing means includes a spacer block slid ably mounted on said pivotal end portion, a spring mounted on said pivotal end portion and engaging said space block for urging said spacer block against said rigid portion, and adjustment means contacting said spring for adjusting the force exerted by said spring on said spacer block.

4. The handling apparatus as claimed in claim 3 wherein said stop means includes a stop bar secured to said pivotal end portion for contacting said rigid portion for limiting pivotal movement of said end portion in the direction said spring means biases said end portion.

References Cited UNITED STATES PATENTS 2,943,750 7/1960 Sehn 294l04 3,150,895 9/1964 Lebre 294-101 FOREIGN PATENTS 1,178,799 9/1964 Germany 294l04 HARVEY C. HORNSBY, Primary Examiner 

